Exhaust system



March 29, 1960 G, 1 FETZER ETAL 2,930,440

EXHAUST SYSTEM INVENTORS. 16J/? 2 Shets-Sheet 1 gg@ Blsazzazef FiledSept. 30, 1957 A trafen/5y.

March 29, 1960 G. L. FETZER ETAL 2,930,440

EXHAUST SYSTEM 2 Sheets-Sheet 2 Filed Sept. 50, 1957 EXHAUST SYSTEMGeorge L. Fetzer and Leonard M. Morrish, Flint, Mich., assignors toGeneral Motors Corporation, Detroit, Mich., a corporation of DelawareApplication September 30, 1957, Serial No. 686,940

Claims. (Cl. 181-54) This invention relates to sound attenuating devicesfor use in the exhaust systems of internal combustion en- Y gines andhas particular relation to muliiers, resonators and other soundattenuating devices adaptable for use in different combinations forattenuating sounds in a wide variety of engine installations.

In the manufacture of motor vehicles it is necessary to be able tosupply a large variety of engines of different displacements,compression ratios, horse power, etc. These require different exhaustsystems, either single or dual exhaust systems and sometimes both foreach engine installation. The variety of mul'llers that are required totune out or mul'lle the objectionable exhaust noises in each of theseinstallations presents a tooling and inventory problem which has becomelarge and objectionable. To solve this problem it is proposed to providea mufller and a number of resonators which can be employed in differentcombinations to provide a variety of exhaust systems that can be tunedto attenuate the sounds in a large number of engine installations.

In the drawings:

Figure l is a fragmentary view of a motor vehicle chassis embodying anexhaust system means embracing the principles of the invention;

Figure 2 is a cross-sectional view of a muflier embodied in the exhaustsystem or systems disclosed by Figure l. Figure 2 is taken in the planeof line 2--2 of Figure 1 looking in the direction of the arrows thereon;

Figure 3 is an enlarged fragmentary perspective view of an acousticalcoupling means embraced in the muffler disclosed by Figure 2.

Figure 4 is a longitudinal sectional view through the mufer disclosed byFigures 1 and 2 and takenV substantially in the plane of line 4-4 onFigure 2 and looking in the direction of the arrows thereon.

Figure 5 is an enlarged fragmentary cross sectionalfview of one of theresonators embodiedv in the structure disclosed by Figure l. Figure 5 istaken substantially in the plane of line S-Son Figure 1 and looking inthe direction of the arrows thereon.

Figure 6 is a longitudinal sectional view of the resonator disclosed byFigure 5.

The frame 10 disclosed by Figure l1 supports an ex haust system 11 whichis adapted to exhaust to the atmosphere at the rear of the vehicle theproducts of combustion from an engine supported at the front of the.

frame and employed in driving the vehicle. Thev exofv a single exhaustconduit means 12or it .mayv be a dual exhaust system consisting of apair of the exhaust conduit means 12 and 13. Single or duel exhaustsystems are employed in motor vehicles having the same engines as wellas with motor vehicles having different engines. In suchinstallations,the exhaust conduit means 12 and 13 may embody mutllers 14and a variety of resonators 16 and 17.

The muliiers 14 may embody casings 18 consisting of haust system 11 maybe a single exhaust system consisting 2, terial 22. The casings 18 haveends 23 and 24 secured toY the ends of the walls 19 and 21 by beads orrolled seamsA indicated at 26. The interiors of the casings 18 are divided by partitions 27, 28, 29, 31 and 32 extending trans-v verselyacross the casings and all being spaced between the end walls 23 andV 24to provide resonating chambers 33,.

34, and 36 and expansion chambers 37 and 38. Resonating chambers 33 aresmall high frequency resonating; chambers located at the inletends ofthe casings 18 while, resonating chambers 36 are large low frequencyreso-4 nating chamberslocated adjacent the outlet ends of thecasings 18.The resonating chambers 34 also are small', high frequency chambers,these being located between,y the expansion chambers 37 and 38 disposedbetween theexpansion chambers 33 and 36. Inlet conduits 39 extendthrough the end walls 23 and the partitions 27, 28

and 29 and supply exhaust gas to the expansion charn-l bers 38. Returnconduits 41 extend through partitions; 28 and 29 and connect theexpansion chambers 37 and. 38. Outlet conduits 42 extend throughpartitions 28, 29,', 31 and 32 and the end wall 24 to connect theexpansion; chambers 37 to the atmosphere at the rear of the vehicle.

Figure 3 illustrates a part of the casing Wall 27 in' which extrusions44 have been struck outbetween pairs.

Ofslits 46. The extrusions 44 provide openings 47 groups of whichprovide acoustical coupling means such..

as that formed in partitions 27 and indicated at 48. The acousticalcoupling means 48 is formed in partitions 27 between the resonatingchambers 33 andexpansion charn-- bers 37 and in directly opposedrelation to the inlet ends. of the outlet conduits 42. Other extrusonsillustrated.

within dot and dash lines provide acoustical coupling means 49 and 51 inthe conduits 39 and 41 respectively and acoustically coupling theconduits 39 and 41 throughthe resonating chambers 34. Another group ofthe extru sions 44 illustrated within dot and dash lines provideacoustical coupling means 52 in the outlet conduits 42. The acousticalcoupling means 52 connect the conduits 42 to the resonating chambers 36through annular acoustical coupling means 53 surrounding the conduit42and within tubes 54 secured to the conduits 42 at 56 andA opening atthe opposite ends into the resonatingcham bers 36. The resonatingchambers 36 extend from parti-'- tions 31 to thewalls 24, the partitions32 being provided with extensive openings indicated at 57 for couplingthe. ends of the chambers 36 without appreciable restriction.4

The close coupling of the high frequency resonating chamber means 33 and34 with the low frequency resonating chamber means 36 through theexpansion chamber means 37 and 38 and the acoustical coupling means 48,

49, 51, 52 and 53 prevents the mufflers 14 from beingv sharply tuned tothe vibrational frequencies of the resonating chamber means 33, 34 and36. Instead of such sharp tuning the coupling means reduces theamplitude of sound attenuation of the frequencies represented by theresonating chamber means 33, 34 and 36 and spreads the tuning throughouta range of frequencies extending from the high frequencies of theresonating chamberV means 33 andV 34 to the low frequency of theresonatingchamber means 36. It is therefore possible to employ themufers 14 for tuning sounds throughout a sound frequency range extendingfrom the high frequencyrepr'esented by the resonating chambers 33, 34 tothe low fre-v low and the frequency range is wide. It is also possibleto use such mufllers in a dual exhaust system in which Patented Mar. 29,1960- throughout the same frequency range but arer of greater` amplitudein one conduit than in the other.

Under such circumstances a resonator such as that indicated at 16 maybeemployed. The resonator 16 also may be formed by employing a casing 61having spaced walls 62 and'63 separated by sound absorbing materialindicated at 64. The ends of the casing are closedvby end walls 66 and67 fastened to the side walls 62 andv63 by rolled 'seams 68. Theinterior of the casing 61 is divided by partitions 69 and 71 intoresonating chambers 72, 73 and 74. Outlet conduit 42 extends through theresonator 16 and is acoustically coupled to the resonating chambers 72,73 and 74 by acoustical coupling means 76, Y77 and 78 formed by the'extrusions'44. rThe' tuning frequency of the resonating chambers 72,73,74'within the resonator 61 may be within the'freq'uen'cy range whichincludes and extends between the frequency of the high frequencyresonating chambers 33 and 34 and the low frequency resonating chamber36 in the mufl'lers 14. Y

The muilers 14 also may be used in the same exhaust system for engineswhere the low frequency sounds are of greater amplitude. To do this itis necessary only to attach single low frequency resonators 17 in theoutlet conduits 42. Y t

Such added frequency resonators will give the exhaust system aiiexibility and range of application which will permit the utilizationof a relatively small number of sound attenuating units in a widevariety of combinations in either single or dual exhaust systems for alargenumbcr of engines.

We claim:

1. An exhaust system for internal combustion engines for motor vehiclesand the like and comprising an elongated casing having transverse'partitions disposed therein and dividing said casing into a plurality ofacoustical Vexpansion and resonating chamber means, there being a pairof said expansion chamber means separated by high frequency. resonatingchamber means at the inlet end of said casing and low frequencyresonating chamber means beyondY said expansion chamber means and saidhigh frequency resonating chamber means and at the outlet Vend of saidcasing,.an inlet conduit extending through one end of said casing andthrough one of said expansion chamber means and ksaid high frequencyresonating chamber means and opening at the inner end thereof into theother of said expansion chamber means, a return conduit extendingthrough said high frequency resonating chamber means and opening atztheopposite ends thereof into said pair of expansion chambermeans, anoutlet pansion and resonating chamber means, there being a pair of saidexpansion chamber means separated by high frequency resonating chambermeans at the inlet end of said casing and low frequency resonatingchamber means beyond said expansion chamber means and said highfrequency resonating chamber means and at the outlet end of said casing,an inlet conduit extending through one end of said casing and throughone of said expansion chamber means and saidhigh Yfrequency resonatingchamber means and opening at the inner end thereof into the other ofsaid expansion chamber means, a return conduit extendingthrough saidhigh frequency resonating chamber means and opening at the opposite endsthereof into said pair of expansion chamber means, an outlet conduithaving the inlet end thereof opening into said one of said expansionchamber means and extending through said high frequency resonatingchamber means and said other of said expansionchamber means and throughsaid low frequency resonating chamber means and outwardly of said casingthrough the opposite end of said casing, means acoustically couplingsaid inlet conduit and said return conduit to said high frequencyresonating chamber means, and means acousticallyrcoupling said lowfrequency resonating chamber means to said outlet conduit, saidexpansion chamber meansv and said high frequency resonating chambermeans and said low frequency resonating chamber means and saidacoustical coupling means being capable of being tuned toattenuateiso'unds throughout a relatively wide frequency range andincluding within isaid range sounds of the same frequency as thefrequency ofY said high frequency resonating chamber means and of thesame frequency as the frequency of said low frequency resonating chambermeans.

3. An exhaust system forginternal combustion-engines for motor vehiclesand the like and comprising, an elongated casing having transversepartitions disposed therein and dividing said casing into a plurality ofacoustical expansion and resonating chamber means, there being a pair ofsaid expansion chamber means separated byfhigh frequency resonatingchamber means Vat the inlet end of said casing and low frequencyresonating chamber means beyond said expansionV chamber means and saidhigh fre- Y quency resonating chamber means and at the outlet endconduit having the inlet end thereof opening into said t one of saidexpansion chamber means and extending through said high frequencyresonating chamber means and said other of said expansion chamber meansand through said low frequency resonating chamber means and outwardly ofsaid casing through the opposite end of said casing, means acousticallycoupling a pair of said conduits to one Vanother' through said highfrequency resonating chamber means, and means acoustically coupling saidlow frequency resonating chamber means to said outlet conduit, saidexpansion chamber means and said high frequency resonating chamber meansand said low frequency resonating chamber means and said acousticalcoupling means being capable of being tuned to attenuate soundsthroughout a relatively wide frequency range and including Within saidYrange sounds of the same frequency as the frequency of said highfrequency resonating chamber means and ofthe same frequency as thefrequency of said low Vfrequency resonating chamber means.

2. An exhaust system for internal combustion engines for motor vehiclesand the like and comprising an elongated casing having transversepartitions disposed therein' and dividing said casing into aplurality ofacousticalexof said casing, an inlet conduit extending through one endof said casing and through one of said expansion chamber means and saidhigh frequency resonating chamber means and opening at the inner endthereof into the other of said expansion chamber means, aV returnconduit extending through said high frequency resonating chamber meansand opening at the opposite ends thereof into said pair Vof expansionchamber means, an outlet conduit having the inlet end thereof openinginto said one of said expansion chamber means and extending through saidhigh frequency resonating chamber means and said other of said expansionchamber means and through said low frequency resonating chamber meansand outwardly of said casing through the opposite end of said casing,additional high frequency resonating chamber means formed in said ycasing'anterior to said one of said expansion chamber means Yandthroug'hrwhich said' inlet conduit extends, means acoustically couplingsaid inlet conduit and said return conduit to said'high frequencyresonating chamber means, means directlyaligned with Vthe inlet endofrsaid outlet'conduit Vandacoustically coupling said additional highfrequency resonating chamber means to said outlet conduit and saidone ofsaid expansion chamber means7 and means acoustically coupling said lowfrequency resonating chamber means to saidoutlet conduit, said expansionchamber means and said high frequency resonating chamber means and saidlow frequency resonating chamber means and said acoustical couplingmeans being capable of being tuned to attenuatesounds throughout arelatively wide frequency range and including within said range soundsof the'same frequency as the frequency' of said high frequencyresonating chamber means and of the same frequency as the frequency ofsaid low frequency resonating chamber means.

4. An exhaust system for internal combustion engines for motor vehiclesand the like and comprising an elongated casing having transversepartitions disposed therein and dividing said casing into a plurality ofacoustical expansion and resonating chamber means, there being a pair ofsaid expansion chamber means separated by high frequency resonatingchamber means at the inlet end of said casing and low frequencyresonating chamber means beyond said expansion chamber means and saidhigh frequency resonating chamber means at the outlet end of saidcasing, an inlet conduit extending through one end of said casing andthrough one of said expansion chamber means and said high frequencyresonating chamber means and opening at the inner end thereof into theother of said expansion chamber means, a return conduit extendingthrough said high frequency resonating chamber means and opening at theopposite ends thereof into said pair of expansion chamber means, anoutlet conduit having the inlet end thereof opening into said one ofsaid expansion chamber means and extending through said high frequencyresonating chamber means and said other of said expansion chamber meansand through said low frequency resonating chamber means and outwardly ofsaid casing through the opposite end of said casing, means acousticallycoupling said inlet conduit and said return co'nduit to said highfrequency resonating chamber means, means acoustically coupling said lowfrequency resonating chamber means to said outlet conduit, saidexpansion chamber means and said high frequency resonating chamber meansand said low frequency resonating chamber means and said acousticalcoupling means being capable of being tuned to attenuate soundsthroughout a relatively wide frequency range and including Within saidrange sounds of the same frequency as the frequency of `said highfrequency resonating chamber means and of the same frequency as thefrequency of said low frequency resonating chamber means, and additionalresonating chamber means within said frequency range and -acousticallycoupled to said outlet conduit externally of said casing and capable ofbeing tuned to attenuate sounds throughout said range and increasing thesound attenuating capacity o'f said system in said range.

5. An exhaust system for internal combustion engines for motor vehiclesand the like and comprising, a pair of elongated casings havingtransverse partitions disposed therein and dividing said casings into aplurality of acoustical expansion and resonating chamber means, therebeing a pair of said expansion chamber means separated by high frequencyresonating chamber means at the inlet ends of said casings and lowfrequency resonating chamber means beyond said expansion chamber meansand said high frequency resonating chamber means at the outlet ends ofsaid casings, an inlet conduit extending through one end of each of saidcasings and through one of said expansion chamber means and said highfrequency resonating chamber means and opening at the inner end thereofinto the other of said expansion chamber means, a return conduit in eachof said casings and extending through said high frequency resonatingchamber means and opening at the opposite ends thereof into said pair ofexpansion chamber means, an outlet co'nduit in each of said casings andhaving the inlet end thereof opening into said one of said expansionchamber means and extending through said high frequency resonatingchamber means and said other of said expansion chamber means and throughsaid low frequency resonating chamber means and outwardly of saidcasings through the opposite ends of said casings, means acousticallycoupling a pair of said conduits in each of said casings to one anotherthrough said high frequency resonating chamber means, means acousticallycoupling said low frequency resonating chamber means to said outletconduits in each of said casings, said expansion chamber means and saidhigh frequency resonating chamber means and said low frequencyresonating chamber means and said acoustical coupled means in each ofsaid casings being capable of being tuned to attenuate sounds throughouta relatively wide frequency range and including within said range soundsof the same frequency as the frequency of said high frequency resonatingchamber means and of the same frequency as the frequency of said lowfrequency resonating chamber means, and additional resonating chambermeans within said frequency range and acoustically coupled to one ofsaid outlet conduits externally of said casing of said outlet conduitand capable o'f being tuned to attenuate sounds throughout said rangeand increasing the sound attenuating capacity of one part of said systemin said range, said part of said system being the part of said systemhaving said additional resonating chamber means.

References Cited in the file of this patent UNITED STATES PATENTS2,020,054 Ford Nov. 5, 1935 2,188,202 Mackenzie Jan. 23, 1940 2,618,354Hedrick No'v. 18, 1952 2,652,128 Cary Sept. 15, 1953 OTHER REFERENCESMotor," March 1932, page 48.

